Control device for fuel injection pumps

ABSTRACT

A fuel quantity control device for fuel injection pumps, wherein the maximum &#39;&#39;&#39;&#39;open&#39;&#39;&#39;&#39; position of a fuel quantity regulating member is limited by an abutment member movable by a piston which is displaceable by hydraulic pressure against a return spring. The said hydraulic pressure is admitted to the piston by a control shuttle disposed within said piston and displaceable with respect thereto by a sensor responsive to a variable.

United States Patent Inventor Heinrich Staudt Markgroningen-Talhausen, Germany Appl. No. 831,470 Filed June 9, 1969 Patented May 11, 1971 Assignee Robert Bosch GmbH Stuttgart, Germany Priority July 13, 1968 Germany P 17 51 701.0

CONTROL DEVICE FOR FUEL INJECTION PUMPS 9 Claims, 1 Drawing Fig.

US. Cl 123/140, 123/ 179A Int. Cl F02d 31/00 Field of Search 123/139, 140, 140 (A), 140.2, 140.3, 140.31, 179 (A), 179

[56] References Cited UNITED STATES PATENTS 2,945,484 7/ 1960 Scherenberg et a1. 123/ 1 79L 2,966,902 1/1961 Nallinger 123/179L 2,988,881 6/1961 Reggio 123/140.3X 3,187,734 6/ 1965 Yingst et a1... 123/179L 3,438,361 4/ 1969 Wagner Primary Examiner-Laurence M. Goodridge Attorney-Edwin E. Greigg PATENTED MAY] 1 19m INVENTOR Heinrich STAUDT his ATTORNEY This invention relates to a control device for fuel injection pumps used particularly in diesel engines preferably provided with electric starter apparatus. The control device is of the type that has a sensor which measures one or more-variables affecting the operation of the engine, such asthe temperature of the coolant, and is provided with a shiftable abutment member which continuously limits the maximum displacement of a control rod varying the fuel quantities ,delivered'by the fuel injection pump.

Control devices of the aforenoted type have the purpose to set the quantities of the fuel delivered by the fuelinjection pump in accordance with the momentary operational conditions of the internal combustion engine. Devices are known in which the abutment member, in all operating conditions, including' the starting phase of the engine, tends to assume a position which is a function of the engine temperature. In such devices, disclosed, for example, in British Pat. No. 529,671, during starting of the engine, particularly-during hot-starting, the control rod of the fuel injection pump is not set to the required fuel quantity. It is a further disadvantage of these known devices that the abutment member is displaced directly by the expansion or contraction forces appearing at the sensor. Since these forces are in general small, other external forces that are exerted on the control rod, affect'the position of the abutment member. An increase of the dimensions of the sensor for the purpose of increasing the forces generated thereby, is usually not possible; further, such an increase in dimensions would decrease the temperature sensitivity of the sensor. 1

OBJECT AND SUMMARY OF THE INVENTION It is a principal object of the invention to provide an improved control device of the aforenoted type wherein the above-mentioned disadvantages are eliminated.

Briefly stated, according to the invention, the abutment member is coupled with a piston slidable in a hydraulic cylinder into which merges a channel associated with a control member which, when the engine starter devices are energized, connects said channel with a conduit to drain hydraulic liquid from said hydraulic cylinder, and which, when said starter devices are deenergized, connects said channel with a pressure conduit, preferably with that of the engine-lubricating system. In this latter condition, the quantity of the hydraulic fluid admitted into the hydraulic cylinder to displace said piston, is determined by the aforenoted sensor.

According to a preferred embodiment of the invention, the sensor displaces, as a function of the measured variable, a control shuttle, which, as a hydraulic servomotor, determines the axial position of the piston of the hydraulic cylinder.

The invention will be better understood aswell as further objects and advantages will become more apparent from the ensuing detailed specification of a preferred, although exem plary embodiment, taken in conjunction with the sole figure which is a sectional, partly diagrammatic, view of the inventron.

DESCRIPTION OF THE EMBODIMENT Turning now to the FIGURE, a bellcrank generally indicated at 1, constituting an abutment member and formed of arms la and lb, is pivotally mounted in a bracket 2. The free end of arm serves to delimit the path of displacement of a fuel control rod 3 associated with a fuel injection pump (not shown). Marks 1, II and Ill indicate different positions of the radial terminal face of the control rod 3. The position of the control rod 3 at mark I corresponds to the fuel quantity necessary for the starting of the engine, mark ll designates the position for full load conditions, while mark Ill indicates the zero fuel position. Arm 1a is provided with an arcuate slot 4, through which extends a securing screw 5 attached to arm 1b, which, like arm 10, is pivotally mounted in bracket 2. By temporarily loosening the screw 5 and moving arm lb pivotally with respect to arm la, the angle between these two arms may be adjusted. The free end of arm 1b is provided with an inwardly extending longitudinal slot slidably engaged by a pin 6 fixedly secured to an ann 6a which, intum, is rigidly attached to a piston 7. For changing the effective length of lever 1b with respect to pin 6, the bracket 2 is displaceable in either direction of arrow 2a. The piston 7 is slidably disposed in a cylindrical chamber 8a of a hydraulic cylinder generally indicated at 8. A compression spring 9 engages, with one end, a shoulder 10 of the piston 7 and engages, with its other end, the inner face of a cap 11 which serves as a closure member for the cylinder chamber 8a. The piston 7 is provided with an axial bore 12 which is closed at its lower end by means of a cap 14, and in which there is disposed a control shuttle 13.

The control shuttle 13 extends upwardly from the bore 12 and projects through an opening 16 of cap 11 beyond cylinder 8. At'its upper terminal portion 15 the shuttle 13 is provided with a transverse pin 17 and, thereabove, with a rim 18. A compression spring 19 is attached to a stationary support 20 and is in engagement with rim 18, thus urging the control shuttle l3 downwardly.

In a channel 21 of the cooling system of the internal combustion engine there is disposed a sensor generally indicated at 22, comprising a housing 23 filled with an expandable material (such as wax) and carrying a downwardly extending displaceable stub 24 having a free terminal radial face 25.

An actuating lever 28 is at its midportion pivotally held in a bracket 30 mounted on a fixed support. One end of lever 28 is formed as a ball-shaped portion 27 urged against the terminal face 25 of stub 24 by a compression spring 26. The other end of lever 28 is formed as a fork 29 which straddles the portion 15 of the control shuttle 13 just below the transverse pin 17 against the force of compression spring 19. The bracket 30 is displaceable in either direction of arrow 30a for the purpose of varying the lever length between the bracket 30 and the pin 17.

With the hydraulic cylinder 8 there communicates a channel 31 intersected by a control member generally indicated at 32 which-as it will be described in greater detail as the specification progresses-is adapted to establish communication either between channel 31 and a return conduit 33 or between channel 31 and a pressure conduit 34 of the lubricating system of the internal combustion engine. The lubricating system comprises an oil pan 35 and an engine-driven oil pump 36 which delivers oil through the pressure conduit 34 across a pressure-responsive control valve 37. A branch conduit 33a of the return conduit 33 merges into the cylinder chamber 8a between the cap 11 and the piston 7.

The control member 32 includes a control pin 39 which is displaceable between two end positions. in a bore 40 by means of an electromagnet 41 against the force of a compression spring 42. The latter engages a rim 43 which is secured to control pin 39 and which is adapted to abut against a shoulder 44 to thus determine the upper end position for the control pin 39.

Channel 31 as well as conduits 33 and 34 of the enginelubricating system merge into bore 40.

The control pin 39 has a control face 45 which is designed in such a manner that in one of the end positions of the pin 39 the channel 31 communicates with the return conduit 33, whereas in the other end position of the control pin 39 channel 31 communicates with the pressure conduit 34. The channel 31 is in continuous communication with a port 46 which merges into the bore 12 of piston 7. Another port 50 in piston 7 merges into axial bore 12 and communicates with a chamber 51 forming part of cylinder 8 and disposed below piston 7.

The control shuttle 13 is provided with two elongated, axially adjacent annular grooves 47 and 48 separated from one another by a raised control face 49 which, depending of the positions of the piston 7 and the control shuttle 13, may either obturate ports 46 and 50, or be disposed thereabove or therebelow. The effect of each of these three positions will become evident as the specification progresses. The lower end wall 52 of the chamber 51 forms an abutment limiting the axial displacement of the piston 7.

From the lower face of the control shuttle 13, there extends a channel 53 to the annular groove 47, thus connecting the former with the return conduit 33 of the engine-lubricating system.

The pressure conduit 34 merges into the bore 40 with a throttle 54 which cooperates with an annular groove 45a in the control pin 39, and the flow passage section of which may be adjustable.

An electric circuit generally indicated at 55 includes a current source 58, a resistance heater 56, a starting motor 57, a main switch 59 for energizing or deenergizing circuit 55 and an auxiliary switch 60 in series with starting motor 57 for controlling the latter when switch 59 is closed. The electromagnet 41 is part of circuit 55 and is connected parallel with the electric devices 56, 57 used for starting the internal combustion engine.

OPERATlON OF THE EMBODIMENT The FIGURE depicts the aforedescribed apparatus in a position when the engine is cold and at standstill and the electric devices 55, 56 for starting the engine are deenergized. The channel 31 communicates through the annular groove 45a with the conduit 34 in which there is no pressure yet since the engine-driven pump is inoperative. Urged by the spring 9, the piston 7 engages the abutment 52 and the arm 10 of the bellcrank 1 connected with the piston 7 permits the fuel control rod 3 to freely shift to a position (mark I) in which the delivered fuel exceeds the full load" fuel quantity. The expanding material (wax) in the housing 23 assumes its contracted volume corresponding to a low temperature so that the stub 24 is, urged by spring 26, deeply pushed into the housing 23. The control shuttle 13, which, through actuator arm 28, is dependent of the position of stub 24, is pushed far down into the hydraulic cylinder 8 under the effect of spring 19. In this position, the ports 46 and 50 in piston 7 are interconnected through the lower annular groove 48.

When, for starting the internal combustion engine, the switch 59 of the electric circuit 55 is closed, and thus the resistance heater 56, the starting motor 57 (if switch 60 is closed) and the electromagnet 41 are energized; the latter pulls the control pin 39 into a position in which the channel 31 is connected with the return conduit 33 and the pressure conduit 34 is closed. Thereby it is prevented that the pressure which slowly builds up in the conduit 34 has any effect on the piston 7 during the starting of the engine. When the engine runs on its own and the resistance heater 56 and starting motor 57 are deenergized by opening the switch 59, the electromagnet 41 also becomes inoperative and consequently, the spring 42 returns the control pin 39 into its position shown in the FIGURE, in which the channel 31 communicates with the pressure conduit 34 of the engine-lubricating system. Now the lubricating oil flows through the channel 31 as well as ports 46 and 50 into chamber 51 and exerts there a force on the frontal radial face of the piston 7. As a result, the piston 7 is lifted against the force of spring 9, while the control shuttle 13 remains stationary. As the piston 7 moves upwardly, it causes a counterclockwise rotation of bellcrank 1 about its pivot in bracket 2. The piston 7 stops in its upward motion as soon as communication is interrupted between ports 46 and 50 by the control face 49 of shuttle 13.

In this position of the piston 7, the free end of arm 1a of the bellcrank l is at mark 11, limiting the maximum open position of the control 3 to full loa fuel quantities.

It is to be noted that the oil pressure, by virtue of the throttle 54, builds up in the chamber 51 in a delayed manner with respect to the electric switching steps; as a result, fuel quantities necessary for the starting of the engine are delivered until the engine is capable of running on its own with full load" fuel quantities.

In case of very low outer temperatures, the frictional forces and the gear resistances increase to such an extent that the internal combustion engine may overcome these opposing forces with full load" quantities only upon reaching a certain r.p.m. In such cases, during the initial phase of the independent operation of the engine-that is, after the starting motor is deenergized-the resistance heater 56 is still operating until the engine runs securely on its own. For such an operation, the deenergizing of starting motor 57 is effected by opening the auxiliary switch 60 which does not affect the current flow through resistance heater 56 or electromagnet 41.

If, during the operation of the engine, the temperature of the coolant in channel 21 of the cooling system exceeds, for example, C., the expandable material in the housing 23 of the sensor 22 expands and the stub 24 is pushed outwardly and downwardly against the force of spring 26. This displacement is transmitted by the actuating arm 28 to the control shuttle 13. As a result, the latter is shifted upwardly against the force of spring 19. As the control shuttle l3 slides upwardly relative to piston 7, the control face 49 moves away from the respective mouths of ports 46 and 50, so that communication is again established between these two ports through annular groove 48 of the control shuttle 13. Thus, there is again communication between pressure conduit 34 and chamber 51, so that pressure may again increase in the latter. As a result, piston 7 is displaced upwardly to follow the control shuttle 13 until the control face 49 thereof again obturates ports 46 and 50 interrupting hydraulic communication therebetween. The aforedescribed further upward movement of piston 7 causes a further counterclockwise rotation of bellcrank 1 and thus the free end of the arm la is moved beyond mark ll. As a result, the full load fuel quantity and engine output are further decreased.

lf, on the other hand, the temperature of the coolant decreases, the contraction of the wax or the like in housing 23 permits the spring 19 to move the control shuttle 13 downwardly. As a result, the control face 49 clears the respective mouths of ports 46 and 50 downwardly, so that communication is established between the pressurized chamber 51 and the return conduit 33 through port 50, upper annular groove 47, cylinder chamber 8a and channel 33a. Thus, oil may drain from the chamber 51. As a result, the piston 7, urged by spring 9, may follow downwardly the control shuttle 13. It is apparent that such a motion of piston 7 causes a clockwise rotation of bellcrank 1, whereby the full load" fuel quantities are increased.

If the engine is stopped, for example, by setting the fuel control rod 3 by means of a cutoff magnet (not shown) to a zero fuel quantity (mark 111), the oil pressure drops in the conduit 34 and the piston 7 moves into engagement with the abutment 52 under the effect of the spring 9.

By providing in circuit 55 a temperature-responsive switch 67 in series with electromagnet 41, the latter will not be energized at high engine temperatures during the starting of the engine, so that the communication between the channels 31 and 34 is continuously maintained. Consequently, during the starting of the engine, the fuel quantity is immediately decreased as the lubricating oil pressure increased. As a result, the undesired smoke generation during the starting of the hot engine is substantially decreased.

Further, in a simple manner, parallel with the sensor 22, control signals emanating from other variables (pressure, temperatures) may be applied and amplified.

The electromagnet 41 may be connected to the circuit 55 in such a manner that its energization depends upon that of the resistance heater 56 and/or of the starting motor 57 and/or of the cutoff magnet.

I claim:

1. ln a fuel quantity control device for a fuel injection pump associated with an internal combustion engine that is provided with electrical starting apparatus, said control device being of abutment member delimiting the path of movement of a fuel quantity control member of said fuel injection pump, said abutment member being displaceable as a function of the condition of said sensor, the improvement comprising,

A. a hydraulic cylinder,

B. a piston reciprocably disposed in said cylinder and operatively connected to said abutment member to cause displacement thereof in response to the motion of said piston,

C. means delivering pressurized hydraulic fluid,

D. a channel connecting said cylinder with said means delivering pressurized hydraulic fluid,

E. movable means disposed in said channel to assume a first position when-said electric apparatus is in a deenergized condition, and second position when said electric apparatus is in an energized condition, said movable means, when in said first position, permitting communication between said channel and said means delivering pressurized hydraulic fluid; said movable means, when in said second position, blocking communication between said cylinder and said means delivering pressurized hydraulic fluid, and

F. control means displaceable as a function of the condition of said sensor means, said control means regulating the admission of said pressurized hydraulic fluid to effect a controlled displacement of said piston.

2. An improvement as defined in claim 1, wherein one end of said cylinder is formed as a chamber in which an end face of said piston is disposed; said control means includes a control shuttle slidably disposed in a bore of said piston; said control shuttle, depending upon the direction of its displacement caused by said sensor means, is adapted to establish communication either between said chamber and said means delivering hydraulic fluid under pressure to cause movement of said piston in one direction relative to said control shuttle, or between said chamber and said draining means to cause movement of said piston in an opposing direction relative to said control shuttle, the movement of said piston in either direction is stopped when said control shuttle, as a result of the relative motion of said piston, blocks all communication with said chamber.

3. An improvement as defined in claim 2, wherein said piston includes a first port connecting said channel with said bore and a second port connecting said bore with said chamber.

4. An improvement asdefined in claim 1, including spring means urging said piston towards an end position against the force of said hydraulic fluid, said piston is in said end position when said movable means is in said second position; when said piston is in said end position, said abutment member is so oriented as to permit such a setting of said fuel quantity control member in which fuel quantities required for starting of the engine may be delivered.

5. An improvement as defined in claim 1, including a pressure conduit connecting said means delivering hydraulic fluid with said movable means, said pressure conduit contains a throttle to delay the flow of said hydraulic fluid through said channel when said movable means is in said first position.

6. An improvement as defined in claim 1, wherein said sensor means contracts or expands in response to changes in the temperature of the coolant in the engine cooling system.

7. An improvement as defined in claim 1, wherein said means delivering hydraulic fluid under pressure is the enginelubricating system.

8. An improvement as defined in claim 1, wherein said movable means is actuated by an electromagnet energized and deenergized simultaneously with the energization and deenergization of said electrical starting apparatus; said movable means assumes said first position when said electromagnet is deenergized, said movable means assumes said second position when said electromagnet is energized.

9. An improvement as defined in claim 8, including an engine temperature-res ns ive switch in series with said elecromagnet, said swi ch IS in an open position beyond a predetermined engine temperature to prevent said movable means from assuming said second position when said electrical starting apparatus is energized for starting said engine in a hot condition. 

1. In a fuel quantity control device for a fuel injection pump associated with an internal combustion engine that is provided with electrical starting apparatus, said control device being of the type that includes (A) sensor means responsive to at least one variable affecting the operation of said engine and (B) an abutment member delimiting the path of movement of a fuel quantity control member of said fuel injection pump, said abutment member being displaceable as a function of the condition of said sensor, the improvement comprising, A. a hydraulic cylinder, B. a piston reciprocably disposed in said cylinder and operatively connected to said abutment member to cause displacement thereof in response to the motion of said piston, C. means delivering pressurized hydraulic fluid, D. a channel connecting said cylinder with said means delivering pressurized hydraulic fluid, E. movable means disposed in said channel to assume a first position when said electric apparatus is in a deenergized condition, and second position when said electric apparatus is in an energized condition, said movable means, when in said first position, permitting communication between said channel and said means delivering pressurized hydraulic fluid; said movable means, when in said second position, blocking communication between said cylinder and said means delivering pressurized hydraulic fluid, and F. control means displaceable as a function of the condition of said sensor means, said control means regulating the admission of said pressurized hydraulic fluid to effect a controlled displacement of said piston.
 2. An improvement as defined in claim 1, wherein one end of said cylinder is formed as a chamber in which an end face of said piston is disposed; said control means includes a control shuttle slidably disposed in a bore of said piston; said control shuttle, depending upon the direction of its displacement caused by said sensor means, is adapted to establish communication either between said chamber and said means delivering hydraulic fluid under pressure to cause movement of said piston in one direction relative to said control shuttle, or between said chamber and said draining means to cause movement of said piston in an opposing direction relative to said control shuttle, the movement of said piston in either direction is stopped when said control shuttle, as a result of the relative motion of said piston, blocks all communication with said chamber.
 3. An improvement as defined in claim 2, wherein said piston incluDes a first port connecting said channel with said bore and a second port connecting said bore with said chamber.
 4. An improvement as defined in claim 1, including spring means urging said piston towards an end position against the force of said hydraulic fluid, said piston is in said end position when said movable means is in said second position; when said piston is in said end position, said abutment member is so oriented as to permit such a setting of said fuel quantity control member in which fuel quantities required for starting of the engine may be delivered.
 5. An improvement as defined in claim 1, including a pressure conduit connecting said means delivering hydraulic fluid with said movable means, said pressure conduit contains a throttle to delay the flow of said hydraulic fluid through said channel when said movable means is in said first position.
 6. An improvement as defined in claim 1, wherein said sensor means contracts or expands in response to changes in the temperature of the coolant in the engine cooling system.
 7. An improvement as defined in claim 1, wherein said means delivering hydraulic fluid under pressure is the engine-lubricating system.
 8. An improvement as defined in claim 1, wherein said movable means is actuated by an electromagnet energized and deenergized simultaneously with the energization and deenergization of said electrical starting apparatus; said movable means assumes said first position when said electromagnet is deenergized, said movable means assumes said second position when said electromagnet is energized.
 9. An improvement as defined in claim 8, including an engine temperature-responsive switch in series with said electromagnet, said switch is in an open position beyond a predetermined engine temperature to prevent said movable means from assuming said second position when said electrical starting apparatus is energized for starting said engine in a hot condition. 